Merc 496 Stuck Valve

Ryanm51981

Member
Apr 10, 2012
78
Boat Info
2006 Sea Ray 290 ----
2006 Sea Ray 38 Sundancer
Current -Ocean Yachts - 48SS
Engines
Mercury
I recently noticed that I was losing about 180 RPMS when throttle was wide open on my merc 496 with 475 hours. Long story short had my mechanic come down and he did a compression check and said that I had a valve that was sticking . He is recommended redoing the head .
Is there any chance this problem will just work itself out over time ? From what I’ve heard a lot of motors start up in the spring time with valves sticking and after The motor warms up it’s fine .
 
I would add a pint Mystery Oil to the crankcase and a pint to the fuel tank as well. Given the time of year in NY you will probably need to wait until next spring. Give the boat a couple of good runs and recheck compression while still warm.
 
just curious...why were you running your motors at WOT? is that something you normally do? or were you doing some sort of sea trial/test? I just picked up a 340 in July with the 8.1 Vdrives and the surveyor ran it at WOT for about 2 min during the test but that was the only time.
 

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